This invention relates to rear-screen projectors and more particularly to those projectors capable of selectively expanding a projected image such that the projection screen may be filled.
A rear-screen projector projects images contained on a slide onto a projection screen contained therein. Ideally, the slides used therewith are of a uniform size format for which the projector is designed. However, with the different size formats in the film used to make the slides, it is not unusual for the projector to be used with slides having a size format different from that for which the projector was designed. In the case where the slide size format is smaller, the projector is not able to fill the projection screen with the projected image. Also in viewing slides, it is sometimes desirable to be able to magnify a portion of the projected image for greater detail.